An optical fingerprint imaging system can implement fingerprint image capturing based on light reflection/refraction, and light sensoring. Specifically, when a finger touches an active area of the optical fingerprint imaging system, light emitted from the fingerprint imaging system will reach the finger and be reflected by the finger. As light reflected by different regions, e.g., ridges and valleys of the finger may have different intensity values, features of a fingerprint corresponding to the finger can be represented based on the light intensities. In some solutions, the reflected light may be received by a sensor where the intensity information thereof is converted into electrical signals. As such, a fingerprint image can be obtained based on processing the electrical signals.
Generally, a backlight is required to provide light for implementing a fingerprint image capturing process. The backlight includes a light source (e.g. a LED) and a light guide plate, wherein the light source is disposed close to a lateral side of the light guide plate. Thus, light emitted from the light source can be guided, by the light guide plate, to the active area of the optical fingerprint imaging system. However, light use efficiency and a stability of the light source may affect an image capturing performance of the optical fingerprint imaging system.
Therefore, an optical fingerprint imaging system, which has improved light use efficiency and a stable light source, is required.